"What do you suppose it is?" she asked, looking it over as we made our way up the rocks again to the car. "Where did it come from?"
We did not see a man standing by our car, but he saw us. It was Del Mar's man who had paused on his way to watch us. As we approached he hid on the other side of the road.
By this time we had reached the car and opened the cylinder. Inside was a note which read:
"Chief arrived safely. Keep watch."
"What does it mean?" repeated Elaine, mystified.
Neither of us could guess and I doubt whether we would have understood any better if we had seen a sinister face peering at us from behind a rock near-by, although doubtless the man knew what was in the tube and what it meant.
We climbed into the car and started again. As we disappeared, the man came from behind the rocks and ran quickly up to the top of the hill. There, from the bushes, he pulled out a peculiar instrument composed of a strange series of lenses and mirrors set up on a tripod.
Eagerly he placed the tripod, adjusting the lenses and mirrors in the sunlight. Then he began working them, and it was apparent that he was flashing light beams, using a Morse code. It was a heliograph.
Down the shore on the top of the next hill sat the man who had already given the signal with the handkerchief to those in the valley who were working on the mining of the bridge. As he sat there, his eye caught the flash of the heliograph signal. He sprang up and watched intently. Rapidly he jotted down the message that was being flashed in the sunlight:
Dodge girl has message from below.
Coming in car. Blow first bridge she
crosses.